Hydraulic drilling machine



A118? 1 1942- g E; J. HIRVONEN 2, 5

' HYDRAULIC DRILLING MACHINE Filed Oct, 28, 1938 S Sheets-Sheet 1 Q Aug. 18, 1942. E J. v 2,293,059

' HYDRAULIC DRILLING MACHINE Filed Oct. 28, 1938 3 Sheets-Sheet 2 v Inuerzi'or,

Y 7 Aug. 18, 1942. E, vouzu 2,293,059

HYDRAULIC DRILLING MACHINE Filed 051. 28, 1938 s Sheets-Sheet s 129.9, v v I ii] Patented Aug. 18,1942

2.293.059 v nrnaamo panama momma Eric J. Hirvonen, Worcester, Mass., assignor to Leland-Gifford Company, Worcester, Mass., a corporation oi Massachusetts Application October 28; 1938, Serial No. 237,510

27 Claims.

This invention relates to hydraulic drilling machines and has particular reference, to a hydraulic drilling machine capable of being operated in many respects like a mechanical sensitive drill.

In a sensitive drilling machine of the purely mechanical type the drill and tl'ie work'are fed together by the manual operation of a lever which, usually, controls the advance and retraction of the-drill.

One of the advantages of the sensitive'drilling machine is that the action of the drill on the work can be felt or sensed by the operator by means of the pressure required to force the drill into the work and hence the operation of themachine can be. governed by the .ieel of, the drill operated drilling machine embodying the present invention.

as gained throughthe operating handle. The

rate of drilling is governed by the rate at which the operator moves the lever and the rate is changed by changing the rate of movement of the lever.

One of the objects of thepresent invention is the provision of a drilling machine where the work and the drill or tool are brought into cutting Fig. 2 is a side elevation of the hydraulic cylinder and piston and control mechanism of Fig. 1, part of the movable work supporting table being broken away.

Fig. 3 is a front elevation of the mechanism of Fig. 2. I

Fig. 4 is a plan view of the mechanism of Fig. 2 taken along line 4-4 of Fig. 3. g 1

Fig. 5 is a side elevation of the hydraulic cylinder of Fig. 3 with the control'mechanism removed.

. Fig. 6 is a plan view of the top end of the cyl- 1 inder of Fig. 5.

Fig. Us a sectional detail-taken along line 1-4 of Fig. 6 illustrating. the construction of the oil passage to the end of the cylinder. t

Fig. 8 is a perspective and more or less diagrammatic view of the block connecting the manually controlled valve mechanism with the hydraulic cylinder and particularly illustrating the 3 oil passages therein.

engagement 'by hy'draulic power mechanismunder, control of an operating handle in such manner that the machine can be operated in many respects like a sensitive drilling machine of the mechanical type.

Another object of the invention is the provisionof a drilling machine where the drill and the work are brought into cutting engagement by hydraulic power mechanism under control of an operating handle, the movement of the work and drill toward and away from each other being accomplished by movements of the handle in opposite direciions and the rate of movement being governed by the rate of movement of the handle.

A further object of the invention is the provision of a drilling machine of the type above outlined where increased pressure on the operating handle is required to effect an increase in the cutting rate of the tool.

A yet further object of the invention isthe provision of a hydraulically-operated manuallycontrolled drilling machine that is capable of automatic operation.

Another object is generally to improve the construction and operation of hydraulically operated drilling machines. I

h "mechanism herein described and claimed is described in my copending application Serial l lo' .3f48;389, filed July 30, 1940.

- Fig. 3.

Fig 1 is .a side elevation of a hydraulically 55 Fig. 9 is anenlarged sectional detail of the control mechanism taken along line 9-9 of Fig. 10 is a section of the control mechanism taken along line Iii-III of Fig. 9.

Fig. 11 is an enlarged sectional detail taken along line Ii--ll of Fig. 9.

Fig. 12 is a sectional detail takenalong line |2|2 of Fig. 11.

Fig. 13 is a sectional detail of the adjustable stop mechanism for the handle taken along line |3--l3 of Fig. 2.

The invention is herein illustrated as embodied in the multiple spindle drilling machine comprising the vertical column supported'on the base 22 and carrying a drill head 24 provided with a plurality of drill spindles 26 which are adjustable as to positions and are driven by the m0tor28. the column 20 is provided with a vertical guideway 30 on which a work supporting table 32 is vertically movable. A hydraulic cylinder 34 is vertically disposed beneath the table and has an outstanding flange 36 at the top by which it is fixed to the under face of the table by bolts 38. The cylinder and the table move vertically as a unit. The lower end of the cylinder is provided with a head' 40 containing a packing through which a vertical piston rod 42 is movably extended, the rod'having a piston 44 at its upper end, see Fig. 3. The lower end of the piston rod has an outstanding flange 46 fixed rigidly to the base 22 by-bolts 48.

The cylinder is provided with a flat vertical pad or flange 50 intermediate its length having an upper port 52 open in its frontface58 which gomunicates with an upwardly directed passage 54 in the wall of the cylinder, the passage at its upper end having a side, outlet 56 which opens into the top part of the cylinder. The pad also has a lower port 58 in its front face which communicates with a fluid passage 80 similar to the passage 54 but extending downwardly and opening into the lower end of the cylinder. A block 62 issecured removably to the face 53 of the pad 50 by bolts 64. Said block, see especially Fig. 8, has a rear face provided with ports 66 and 88 which register respectively with the ports 52 and 58 of the cylinder. Said ports 66 and 68 communicate with internal passages and 12 in the block which terminate in vertically disposed upper and lower ports 14 and 16 in the side face 16 of the block. Said side face also has a high pressure oil inlet port 80 disposed intermediate the ports 14 and 16 and forwardly of the vertical line through said ports. Said port 80 communicates with a passage 82 which communicates with a port 84 in the lower face of the block. The port 84 communicates with a flexible high pressure oil pipe 68 the other end of which is secured to a junction box 90 fixed tothe side face of the column 20.

Said junction box and high pressure conduit receive high pressure 011 through a pipe 92' from a constant speed motor driven gear pump unit 94 which unit is provided with means not necessarily shown to maintain a constant oil outlet pressure irrespective of the demand for oil on the unit. Said unit is mounted upon the top of an oil storage tank 96 into which exhaust or low pressure oil from the system is discharged, as will presently be explained, o be recirculated by-the issued April 25, 1933.

A control casing or housing 88, having aside face I00 bolted to the side face 18 of the block 62,

carries valve structure and manual operating mechanism therefor for effecting control of the table 32. The face I00 has ports I04 and I06, see Fig. 9, which register with the cylinder ports 14 and 16 respectively of the block 62 and a third port I08 which registers with the high pressure port 80. The ports I04 and I 06 thus communicate with the top and bottom of the cylinder respectively while the port I08 communicates with the high pressure oil supply.

The casing 98, see especially Figs. 9 and 10, is provided at one side thereof with a vertical cylindrical bore or passage I I0 which is surrounded by vertically spaced annular oil recesses or channels II2, I I4, I I6, respectively, separated by intervening ribs H6, I20,respectively. The channels H2, H4, H6 communicate respectively with the ports I04, I06, I06. Thus the upper channel II2 communicates with the top of the hydraulicf cylinder, the channel II6 with the bottom of the cylinder, and the channel I I4 with the high pressure oil inlet.

A cylindrical sleeve or bushing I22, comprising a valve cylinder, is received snugly within the cylindrical passage I I0 so that the oil cannot flow directly between the channels I I2, I I4, and H6. The bushing has an internal cylindrical bore or passage I24 therein and vertically spaced internal groovesor channels I26, I28 and I30, registering and communicating respectively therewith A through a series of holes I32, drilled or otherwise formed through the wall of the valve cylinder.

A tubular or hollow cylindrical valve member or piston I34 is freely movable within the passage I24 of the bushingand is provided with piston sections I86, and I38 near its ends and intermediate piston sections I31 and I89,respectively, which latter sections in the normal or at rest position of the valve and the machine confront the oil channels I26 and I30 and are axially wide enough to close said channels so that no oil can flow from the high pressure channel II4 through the annular groove I40 between the pistons to either the upper or the lower parts of the cylinder; nor can any oil flow out of these parts of the cylinder. Movement of the valve either upwardly or downwardly, however, places one cylinder port in communication with the high pressure port and the other cylinder port in communication with the exhaust.

Communication with the exhaust is established by annular grooves or channels I42 and I 44 located at the upper and lower ends of the valve respectively and above and below the pistons I 36, I38 and communicating through drilled holes I46 and I 48 respectively with the interior passage I50 of the valve piston. The oil escapes from the interior of the valve through a tube I52 which is fixed in a cover plate I 54 having an annular wall I56 that is screw-threaded into the bottom end of the cylinder passage IIO of the casing 98. The exhaust oil flows from the'tube I52 into the chamber I56 under the cover plate and thence into an exhaust connection I62 screw-threaded in a plug I63 threaded into the bottom of the passage IIO. A flexible pipe I64 connects the exhaust connection I06 with the aforesaid junction box 90 from whenee the oil flows through a pipe I66 to the tank 96.

The bushing or valve cylinder I22 is held against axial displacement in the passage IIO by being seated upon the upper end of the with the channels H2; H4, H6, respectively,

side wall I56 of the bottom cover plate I54 and at the upper end by being seated against an annular ring I68 which bears against an internal shoulder of the passage H0 and also upon an upper closure plate I10 which is screw-threaded into the-upper end of the passage.

Spring mechanism is provided to maintain the valve piston I34 yieldingly in a normal or mid position thereof where both cylinder ports are closed and the table is locked against movement by reason of confinement of oil in both ends of the operating cylinder; and also to tend to return the valve member to said position when displaced therefrom under control of the 0perative.

Said spring mechanism includes an upper spring carrying disc or plate I12 which bears upon the top or end wall I14 of the valve piston within the spacer ring I68 and is larger in diameter than the valve member and extends outwardly therebeyond and also bears upon the top end face received in recesses of the closure. member I64. The disc I18 bears against the lower face of the journalled in the hub 28 4 by anti-friction rolls 2l8. The shaft at its outer end passes loosely valve member and radially outstands said-face,

tial pressure has to be overcome to move the valve piston in either direction. The springs are of short axial extent so that their resistance to compression increases rapidly with a shortening of their lengths. The valve piston and cylinder are substantially coextensive in length so that there is no harmful lost motion of the valve piston in shifting its application of pressure from one to the other set of springs under man-- ual operation.

' under substantial initial stress so that their ini- I The lower ring I18 is held against relative rotation with respect to the closure member I54 by means of a pin I82, see Fig. 11, carried by the,

closure memberand upstanding loosely within a passage I84 of the ring. The upper disc I12 is similarly held against relative rotation with respect to the cover member I18.

The space between the lower end of the valve member I 34 and the interior of the closure member I54 is adapted to form a dash pot chamber containing oil to steady the movements 'of the valve piston, or the relative movement between the valve and the casing 98 so that the action of the table will be smooth. To this end the exhaust tube I62 extends upwardly within the lower end of the tubular passage in the valve member and is provided with reasonably oil tight sliding engagement therewith preferably by a piston ring I86 bearing against the inner sidewall of the valve member and held against axial movement by the outstanding shoulder I88 of the tube I52 and also by the bottom wall I98 of the closure member I54.

The valve member or piston is moved verticall by a vertical valve rod I92 screw-threaded at its lower end into the end wall I14 of the valve member and having a head I84 which is seated against the inner face of the end wall. A check nut I9 6 is screw-threaded on the valve stem and bears against the outer face of the end wall. Passages I98 through the stem and nut I96 allow exhaust oil, which is under a slight pressure, to flow into the spring space above the valve member to lubricate the parts andalso to dampen the action'of the valve.

through the cover plate 2l8 and .has clamped thereon an arm 228. Said arm has an operating handle 222 fixed thereto which extends forwardly under the table 82 ton position in front of the table where it can be readily grasped and operated by an operative. The arm 228 extends on the side of the shaft 2 opposite the handle and is suiiiciently weighted to counter-balance the handle so that the handle preferably will stay .in

any position in which it is placed without movement away from such position.

The other end of the shaft 2l4 has fixed thereto a gear sector 224 which meshes with the teeth of a vertical rack 228 vertically movable through a boss 228 of the casing 98 or more accurately, the casing 98 is movable vertically over the rack. The rack at itslower end passes into a housing 238, see Figs. 1 and 2, fixed to and upstanding from the base 22 of the machine. The housing is vertically split in a well known manner and.

can be contracted about the rack 220 by means of the clamping handle 232 so as to hold the rack stationary. So far as the present invention is concerned the rack is held stationary at all times.

The manner of operation is essentially as follows: 7

If the table is to be moved upwardly the handle is raised upwardly. This causes the gear sector 224, to rotate 0n the rack 226, the gear sector and the rack constituting a movable pivot for the handle. The upward movement of the handle raises the lever structure about its pivot 2I2 and consequently raises the valve I34 so that high pressure oil flows from the intermediate high pressure oil channel Il4'into the u p r channel I I2 of the operating cylinder and thence to the top of the cylinder above the stationary piston and consequently forces the table unwardlv. At the same time the lower end of the The valve stem passes movably through a packing gland 288 of the top cover plate I18 fixed in the end wall of the enclosing casing 98.

Thus vertical movements of the lever structure, including the arm 282, the hub 284, and the arms 286, correspondingly move the valve.

The leverstructure is moved about the stud 2I2 by a shaft 2I4 which extends through and is cylinder is placed in communicati n with the exhaust through the channel H6. Hence the table is caused to be moved upwardly at a rate depending upon the extent of displacement of the valve member, which determines the rate of flow of oil into the upper end of the cylinder and the rate of escape of oil from the lower end of the cylinder. l

Since, however, the casing 98 is fixed to the operating cylinder and hence moves upwardly with the table the pivot 2"! acts on the lever structure to cause it to fulcrum in a counterclockwise direction about the shaft H4 or in a direction to close the valve I34. Thus if the operating handle were only moved upwardly a slight extent and held in this displaced position the table would move upwardly only until the upward movement of the pivot 2I2 had caused the valve to reclose. Thus the table tends constantly to close the valve. Hence to effect continuous upward movement of the table the hamdle must be elevated in a continuous manner. The same action takes place upon downward movement of the table.

Release of the handle causes the instant stoppage of the tabfe due to the resetting of the-valve by the table movement and one or another of the sets of springs I16 and I88. The rate of movement of the table is controlled by the rate of movement of the handle since the rate of movement of the table is dependent upon the extent of displacement of the valve member "and alsosince the table tends to close the valve. For any be moved continuously at a rate suflicient to maintain a required displacement of the valve member.

The springs I16 and I80 are intentionally made short so that their resistance to compression increases rapidly as they are compressed. 'Ihus additional effort is required to be exerted on the handle to obtain additional displacement of the valve in either direction. This corresponds to the increased pressure required to be applied to the handle of a mechanical sensitive drill to obtain an increased rate of drilling.

In the actual machine there is no perceptible lost motion, or time interval, between movement of the handle and corresponding movement of the table. The table goes up and down smoothly and instantly with corresponding movements of the handle and stops instantly when the handle movement is stopped. Increased pressure is required to be exerted on the handle to provide increased movement of the table. Increased resistance to table movement by the drills causes increased pressure to be applied to the handle since the table tends to slow down due to the increased resistance ofdrilling and hence causes the upper set of springs M6 to be compressed further to maintain the speed of the handle and to increase the displacement of the valve member. The compression of the springs also places direction to oppose its movement.

The handle is provided with an adjustable stop to limit the upward position of the table. Said stop comprises a sleeve 234, see Fig. 13, on

. a bolt 236 movablein anarcuate T-groove 238,

see also Fig. 2, and screw-threaded into a nut 24!! slidable along the base portion of the groove.

aaaaoso ments of said movable element and the stop position thereof as determined by the forward and .rearward movement and the stop position of into different positions under the will of the operator for controlling said table, means controlled by said handle for controlling said hydraulic means to effect corresponding action and position of said work support, and means controlled by movement of said work support when said handle is stationary for moving said handle controlled means into positionwto arrest movement of said work support.

4.111 a hydraulic drilling machine, a tool holder, a reciprocable work support, a hydraulic piston and cylinder for reciprocating said support, valve means including a movable element controlling the inlet and outlet of fluid to and from opposite ends of said cylinder, an operating handle controlling said movable element and movable in diiierent directions and different amounts to condition said valve means to eflect 0 movement of said table in different directions additional 'force on the operating handle-in a 40 The stop can be shifted along the groove by I backing oi! the bolt and moving it into the de sired position and re-tightening it.

I claim:

1. In a hydraulic drilling machine, a tool holder. a work support, hydraulic mechanism for effecting movement of one of the aforesaid elements relatively to the other; valve mechanism for controlling said hydraulic mechanism, an operating handle for said valve mechanism movable in opposite directions for effecting said relative movement in opposite directions, and control means associated with said valve mechanism, movable element and handle and responsive to movements of said element and handle whereby said movable element is caused to respond hydraulically in direction and speed to the direction and speed of movement of said handle.

2. In a hydraulic drilling machine, a tool holder, a work support, hydraulic means for eiiecting movement of one of the aforesaid elements relatively to the other element, an operating handle, and control means associated with saidwliandle and with said hydraulic means and movable-independently by said handle and said movable element for efiecting movement of said movable element at a rate corresponding to the rate of movement of said operating handle and for controlling the forward and rearward moveand different amounts, means associated with said handle and valve means for effecting movement of said work support in a direction corresponding to any selected direction of movement of said handle and at a rate of speed corresponding to the rate of speed of movement of said handle, and means responsive to movement of said work support and responsive to a stationary position of said handle for moving said movable element into a position to arrest movement of said work support.

5. In a hydraulic drilling machine, a tool holder, a work support, hydraulic means for effecting movement of one of the aforesaid elements relatively to the other, valve means controlling the operation of said hydraulic means having a valve member movable with the movable element and a cooperating second valve member, an operating handle movable to move said second valve member in a selected direction, and means responsive to movement of said movable element acting in a direction to move said second valve member in the opposite direction.

6. In a hydraulic drilling machine, a tool holder, a work support, hydraulic means effecting movement of one of the aforesaid elements relatively to the other element,- an operating handle, and valve means for said hydraulic means having a movable member provided with connections with said handle and said movable element for movement in opposite directions by said handle and element.

7. In a hydraulic drilling machine, the combination of a tool holder, awork support, hy-

dle, said handle having a shiftable pivotal support which changes its position with change in position of the handle. v I

8. In a hydraulic drilling machine, a drill holder, a movable work support, hydraulic means support and the pisto .movements of said support.

absence from said tool holder, a fixed member, an operating handle having .pivotal engagement with said fixed member, and a cylinder valve controllingsaid hydraulic means, the cylinder of said valve being connected. a d movable with said of said valve having means connecting the valve piston for movement by said handle and also by said support, said valve having hydraulic connections with said hydraulic means by which movement of said handle effects a movement of said support in the corresponding direction and movement oi said-valve cylinder in a direction to close the valve, and" said valve piston having connections with said movable support tending constantly to efiect closing of said valve in response to 9. In a hydraulic drilling machine,, a tool holder, a movable work support, hydraulic means for reciprocating said support toward and away from said tool holder, a fixed support, an operating handle having a shiftable pivotal engagement with said'fixed support, valve means controlling said hydraulic means including a valve cylinder carried by and movable with said movable work support, a valve piston in said cylinder, a lever operatively connected at one end with said piston and having a pivotal connection at its other end with said movable work support and an intermediate pivotal connection with said handle.

10. In a hydraulic drilling machine, a tool holder, a movable work support, hydraulic means for reciprocating said support toward and away from said tool holder, a fixed s port, an operating handle having a shiftable pivotal engagement with said fixed support, valve means controlling said hydraulic means including a valve cylinder carried by and movable with said movable work support, a valve piston in said cylinand said worksupport operative to hold said work support stationary in any position of said work support within its range corresponding to any stationary position of said handle within its range of movement.

13. In a hydraulic drilling machine, a tool holder, a movable work support, hydraulic means for reciprocating said support toward and away from saidtool holder, valve mechanism controlling said hydraulic means including a movable valve member having a connection with said handle and movable with said handle tending to admit fiuid to said hydraulic means in a direcder, a lever operatively connected at one end with said piston and having a pivotal connection at its other end with said movable work support and an intermediate pivotal connection with said handle, and hydraulic ducts connecting said valve means and hydraulic means by which movement of said operating handlemoves said lever and valve piston to open said valve and eiiects the movement of said movable work support andvalve cylinder and lever'in a direction tending to close the valve.- d

11. In a hydraulic drilling machine, a tool holder, a movable work'support, hydraulic means for reciprocating said support toward and away from said tool holder, valve means controlling movement of said handle and in the opposite direction by movement of the movable support. 12. In a hydraulic machine, a tool holder, a

movable work support, hydraulic means for reciprocating said support toward and away from said tool holder, valve means having a movable tion to move said support in opposite directions an amount corresponding to the direction and amount of movement of said handle and having a connection with said support and movable with said support in a direction tending to arrest the flow of hydraulic fluid.

14. In a hydraulic/drilling machine, a tool holder, a vertically movable work support, hydraulic means for reciprocating said support toward and away from said tool holder, a fixed vertical rack, an operating handle having gear teeth meshing with said rack and valve mechanism controlling said hydraulic, means including a valve cylinder carried by said worksupport and a piston valve, and a lever having an operative connection with said valve piston and pivotal connections with said handle and with said work support. I

15. In a hydraulic drilling machine, a tool holder, a vertically movable work support, hydraulic means for reciprocating said work support toward and away from said tool holder, valve mechanism controlling the operation of said hydraulic means including a valve cylinder carried by said work support, a valve piston movable in said cylinder, a lever having an operative connection at one end with said valve piston and at its other end having a pivotal connection with said work support, a fixed vertical rack, and an operating handle having a pivotal connection with said lever, and gear teeth meshing with said rack.

16. In a hydraulic drilling machine, a tool holder, a work support, hydraulic means for mcv- .ing one oi the aforesaid elements relatively to the other element, valve mechanism controlling moving one of the aforesaid elements relatively to the other element, control means for said hydraulic means including an operating handle movable in opposite directions the position of which determines the position of said movable element and the rate of movement of which in both of its opposite directions of movementdei termines the rate of movement of said movable control member controlling said hydraulic means,

an operating handle, and connections between said control-member and said operating handle 7;

holder, a work support, hydraulic means for means yieldingly opposing the movement of said it.

handle with increased effort for increased rate of movementoi said handle, said last named means including oppositely disposed springsyieldingly opposing. movement of 'the handle in opposite directions, said springs being or short axial length and acting with increased efiort on said handle for increased change of length of the springs.

19. In a hydraulic drilling machine, a tool holder, a work support, hydraulic means for moving one of the aforesaid elements relatively to the other element, a fixed support, an operating handle pivoted on said fixed support, valve mechanism controlling said hydraulic means including a valve cylinder carried by said movable element, a valve piston in said cylinder connected with said handle and also with said movable element for movement by both, and oppositely acting springs acting on said valve piston tending to hold it in a predetermined position against displacement in opposite directions.

20. In a hydraulic drilling machine, a tool holder, a work support, hydraulic means for moving one of the aforesaid elements relatively to the other element in opposite directions, anoperating handle movable in opposite directions, valve mechanism controlling said hydraulic means including a valve cylinder, a valve piston in said cylinder connected with said handle for movement in opposite directions thereby, and springs acting on opposite sides of said piston to maintain it yieldingly in a predetermined position against displacement in opposite directions.

21. In a hydraulic drilling machine, a tool holder, a work support, hydraulic means including a cylinder and piston for moving one of the "aforesaid elements relatively to the other element in opposite directions, a fixed support, an

operating handle movable in opposite directions having pivotal engagement with said fixed support, valve mechanism controlling said hydraulic means including a valve cylinder movable with said movable element and having ports controlling the flow of fluid to and from opposite ends of said hydraulic cylinder, a valve piston in said cylinder having a connection with said handle for movement in opposite directions thereby, and spring means acting in opposite directions on said valve piston to yieldingly maintain said valve piston in a port closing position against displacement in opposite directions.

22. In a hydraulic drilling machine, a tool holder, 9. work support, hydraulic means including a piston and cylinder for moving one of the aforesaid elements relatively to the other element in opposite directions,- a fixed support, an

. operating handle movable in opposite directions an exhaust port, a piston valve in said cylinder arranged to control both hydraulic cylinder ports simultaneously, said valve piston having an operative connection with said handle for movement in opposite directions thereby, a plate at each end of said piston and cylinder abutted against the ends of both, and spring means acting on said plates and operative to maintain said plates yieldingly in the aforesaid position to maintain said valve piston yieldingly in cylinder port closing position against displacement therefrom in opposite directions.

23. In a hydraulic drilling machine, a tool holder, 9. work support, hydraulic means including a cylinder and piston for moving one of the 1 aforesaid elements relatively to the other eleto the other element, a pivoted operating handle, valve mechanism controlled by operation of said hydraulic means including a cooperating valve cylinder and valve piston, one being movable by said handle and the other by said movable element, and means cooperating with the ends of said valve cylinder and piston forming dash pots controlling the movements of said valve cylinder and piston.

25. In a hydraulic drilling machine, a tooland lower ends of said hydraulic cylinder, a valve piston in said valve cylinder, a lever having a connection with said valve piston and a pivotal connection with said housing, a fixed vertical rack, an operating handle having a pivotal connection with said lever and a gear tooth connection with said rack, and spring means opposing displacement of said lever and valve piston in opposite directions.

26. In a hydraulic drilling machine, a tool holder, a work support, means including a hydraulic cylinder and piston for effecting movement of one of the aforesaid elements relatively to the other element, a hydraulic circulatory system associated with said cylinder and piston ior admitting fluid into and out of opposite ends of the cylinder for moving said movable element in opposite directions, an operating handle, valve means including a movable valve member having a connection with and movable under control of said handle operative to admit fluid into a-selected end oi? said cylinder and the escape of fluid from the opposite end of the cylinder to effect movement of said movable element in a selected direction, said movable valve member also having a connection with and movable under control of said movable element in a direction tending to oppose such admission and escape oi fluid.

2'7. In a hydraulic drilling machine, a tool holder, a movable work support, a hydraulic motor for moving said work support toward and away from said tool holder, an actuating memher arranged for different amounts of movement away from a neutral position to eflfect corresponding amounts of movement of said work support, a valve controlling operation of said motor and having a movable valve member displaoeable from a neutral position to secure operation of said motor, means responsive to the movement unoperative position;

of said actuating member for maintaining said valve member in displaced motor-operating position, and means responsive'to the cessation of movement 01 said actuating member for movin; said movable valve member to neutral motor- ERIC J, mRvoNEN; 

